This invention relates to an electrical connector and more particularly relates to an electrical connector adapted to be located in or on the steering wheel of a motor vehicle, for example to establish electrical contact with an igniter for an inflatable air bag which is disposed at the centre of the steering wheel. Such air bags have been proposed before. The igniter, when electrically activated, serves to initiate operation of a gas generator, for example when the vehicle is involved in an accident situation such as a collision. Gas from the gas generator inflates the bag, so that the bag can protect a person within the vehicle from injury.
Because the steering wheel rotates relative to the main part of the steering shaft housing, it is necessary for an electrical connection leading to the igniter to be adapted and arranged to withstand the rotations of the steering wheel. Normally the steering wheel can rotate only a limited number of turns in each direction from a normal or central position.
It has been proposed (see, for example, U.S. Pat. No. 4657326) to use an electrical connector which comprises a flat cable which is coiled to form a spiral lying within a plane. The plane defined by the cable is located at 90.degree. to the plane defined by the spiral, and thus the flat cable is disposed "on edge" in each turn of the spiral. The flat cable is connected, at the inner end and at the outer end of the spiral, to connecting wires which project out of the plane of the spiral, in opposite directions. The connecting wires extend substantially perpendicularly to the plane of the spiral. The connecting wires, which can be round cables, are connected to the conductors present in the flat cable by soldering or by contact pins.
This known electrical connector arrangement has the advantage that the spiral permits considerable movement of the steering wheel in both directions without any risk of the cable breaking. If the steering wheel is turned in one sense the turns of the spiral contract, whereas if the steering wheel is turned in the opposite sense the turns of the spiral expand. The number of turns in the spiral is chosen based on the number of turns of the steering wheel in each direction from the normal position. This prior proposed arrangement also utilises round cable as connecting wires which have significant strength. However, the arrangement does suffer from the disadvantage that establishing contact between the round cables and the flat cable, utilising either solder or pins, is relatively expensive, and also gives rise to a considerable risk that the solder or pins may fail. This is a major disadvantage since it is not really practicable to check the circuit passing through the connector without actually operating the igniter.
The same U.S. Pat. No. 4657326 also discloses a proposal in which a flat cable is formed into a spiral as described above, but the ends of the cable are each bent completely back upon themselves along a line extending, in the plane of the cable, at 45.degree. to the axis of the cable. Thus each end of the cable is bent back upon itself and extends out of the plane defined by the spiral. This bent portion may be restrained in a holder or nipple, and the holder or nipple may be adapted to oscillate in a bearing about an axis which is again perpendicular to the axis of the plane defined by the spiral. This arrangement, although overcoming the problems encountered using soldering or contact pins, leads to the disadvantage that the end portions of the cable, which extend away from the plane of the spiral, are of relatively small cross-section and may thus not have sufficient tensile strength.